radiobuttontest.java

Java编程例子(全新)演示基础的Java 功能,例如类,对象的使用,过程的调用,.

/**
   @version 1.32 2004-05-05
   @author Cay Horstmann
*/

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class RadioButtonTest
{
   public static void main(String[] args)
   {  
      RadioButtonFrame frame = new RadioButtonFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
   }
}

/**
   A frame with a sample text label and radio buttons for 
   selecting font sizes.
*/
class RadioButtonFrame extends JFrame 
{  
   public RadioButtonFrame()
   {  
      setTitle("RadioButtonTest");
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.PLAIN, DEFAULT_SIZE));
      add(label, BorderLayout.CENTER);

      // add the radio buttons 

      buttonPanel = new JPanel();
      group = new ButtonGroup();

      addRadioButton("Small", 8);
      addRadioButton("Medium", 12);
      addRadioButton("Large", 18);
      addRadioButton("Extra large", 36);

      add(buttonPanel, BorderLayout.SOUTH);
   }

   /**
      Adds a radio button that sets the font size of the 
      sample text.
      @param name the string to appear on the button 
      @param size the font size that this button sets
   */
   public void addRadioButton(String name, final int size)
   {
      boolean selected = size == DEFAULT_SIZE;
      JRadioButton button = new JRadioButton(name, selected);
      group.add(button);
      buttonPanel.add(button);

      // this listener sets the label font size

      ActionListener listener = new 
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               // size refers to the final parameter of the addRadioButton method
               label.setFont(new Font("Serif", Font.PLAIN, size));
            }
         }; 

      button.addActionListener(listener);
   }
 
   public static final int DEFAULT_WIDTH = 400;
   public static final int DEFAULT_HEIGHT = 200;  

   private JPanel buttonPanel;
   private ButtonGroup group;
   private JLabel label;

   private static final int DEFAULT_SIZE = 12;
}